Generally, electric current supplied to the windings of a bobbin on a stator are continuously switched in order to switch a magnetic field within an electric motor. The switching of the magnetic field causes rotation of a rotor that is positioned inside of the stator. For example, an electric motor disclosed in a patent document 1 (i.e., Japanese Patent Laid-Open No. 2002-125353) has windings that are wound on a winding part of a bobbin, in which the winding part has a guide groove for retaining the winding.
However, in the electric motor in the patent document 1, the winding is wound on the winding part in plural layers. Further, the winding is not actually retained on the winding part except for the first layer of the winding, which is closest to the winding part. Therefore, the winding may possibly collapse in the course of being wound on the winding part. That is, the shape of the winding may become disorderly and out of shape.